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Re: [Pan-devel] Re: newsrc with DB

From: K. Haley
Subject: Re: [Pan-devel] Re: newsrc with DB
Date: Fri, 11 Jun 2004 02:08:44 -0600
User-agent: Mozilla Thunderbird 0.6 (Windows/20040502)

Duncan wrote:

If you are going to start hashing millions of msg-ids, it might be a
/very/ good idea to go read what Hans Reiser has to say about that, based
on his work with ReiserFS.  There are at least three hash options one can
use with ReiserFS, one that it says not to use, one that is the default
for normal use, and one that he says could be used if the default version
produces hash collisions (which he says shouldn't normally happen until
one gets well into the millions of files -- per directory -- range).

I checked out the info on ReiserFS. The reason it has problems with hash collisions so early is because it can only use 23 bits of the hash. It uses the hash as the cookie for readdir which is a signed int32. Since we can use either 64 or 128 bits there /should/ not be a problem with collisions.

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